This is a very nitpicky question. As I see it, the 3 main concepts tested are:
Above the level of the brainstem (thalamus & cerebral cortex), you have second order sensory neurons. Lesions in this part of the circuit are not generally in trigeminal neuralgia. I suppose they also want us to assume that once the spinal tract of the trigeminal enters the medulla, it's not myelinated anymore. I don't think this is completely true, but given the logic described above, pons would still be the better answer.
As people have pointed out, the primary sensory fibers carrying light touch sensation from the face synapse on the chief sensory nucleus in the pons immediately after they enter the pons. This question is not asking about those fibers though.
I got the question wrong too..
The mnemonic I like for remembering the locations of the cranial nerves is the "2,2,4,4 rule"
Above brainstem= CN I + II Midbrain= CN III, IV Pons= CN V, VI, VII, VIII Medulla= CN IX, X, XI, XII
Principle Sensory Nucleus of the Trigeminal is located in the Pons, as is the Motor Trigeminal Nucleus of the pons. This presentation is probably dealing more with the Principle Sensory Nucleus.
The pons has nerves 5-8, so the trigeminal would be affected here
I do understand that the principal nucleus of the trigeminal nerve is located at the pons. But since this patient is having trigeminal neuralgia wouldn't you be disrupting the pathway involved in pain and temperature, which in this case would be the spinal nucleus (located in the medulla)?
Besides, I found this at an article
A recent hypothesis attributes the pain of trigeminal neuralgia to a central mechanism involving the pars oralis of the spinal trigeminal nucleus.
MS is a demyelinating disease. That's why I didn't pick cortex or thalamus; they are grey matter. I picked medulla because I the spinotrigeminal nerves traverse the medulla. I guess we are just supposed to assume the demyelination is happening in the pons? I don't know.
Per boards and beyond, in the lateral pons is there is the spinal V nucleus which carries contralateral pain and temperature. Knowing that + CN V arises it in the pons, I went with pons. The only other option I had left not crossed out was cerebral hemisphere but that seemed to broad.
theres an association made in 2017 with trigeminal neuralgia and MS - which is what i think this pt has. key thing to note is that while all motor and sensory fibers of CN 5 enter at the level fo the pons (however some also do enter at the level of medulla and even the sc via the spinal tract of 5 to synapse with the long sensory nucleus of 5) heres the link of trigeminal neuralgia and MS: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5649347/